A radio access method and a radio network for cellular mobile communication (hereinafter referred to as “Long Term Evolution (LTE)”, or “Evolved Universal Terrestrial Radio Access (EUTRA)”) are under study in the 3rd Generation Partnership Project (3GPP). In LTE, a base station apparatus is also referred to as an evolved NodeB (eNodeB), and a terminal apparatus is also referred to as user equipment (UE). LTE is a cellular communication system in which the landscape is divided, in a cellular pattern, into multiple cells, each served by a base station apparatus. A single base station apparatus may manage multiple cells.
Here, LTE supports Time Division Duplex (TDD). LTE that employs a TDD mode is also referred to as TD-LTE or LTE TDD. TDD is a technology that enables full duplex communication in a single frequency band by time-multiplexing an uplink signal and a downlink signal. Furthermore, LTE supports Frequency Division Duplex (FDD).
Furthermore, application of an interference reduction technology and a traffic adaptation technology (DL-UL Interference Management and Traffic Adaptation) to TD-LTE is under study in the 3GPP. That is, the traffic adaptation technology is a technology that changes a ratio of an uplink resource to a downlink resource according to uplink traffic and downlink traffic. The traffic adaptation technology is also referred to as a dynamic TDD.
As a method of realizing the traffic adaptation, a method of using a flexible subframe is proposed in NPL 1. The base station apparatus can transmit a downlink signal or receive an uplink signal in the flexible subframe. The terminal apparatus regards the flexible subframe as a downlink subframe as long as the base station apparatus does not instruct the terminal apparatus to transmit an uplink signal.
Furthermore, as an interference reduction technology, Transmission Power Control (TPC) for uplink is under study in NPL 2. For example, study on parameters associated with the transmission power control for uplink is described in NPL 2.